This invention relates generally to detecting positions of actuators, and more particularly to sensing magnetic field angles that are indicative of the positions of actuators.
An actuator is a mechanical device for moving or controlling another device. An actuator may be used to control a valve such that the flow of liquid, gas, or lose material in bulk may be started, stopped, or regulated by opening, shutting, or partially obstructing one or more passageways. The status of the valve (open, shut, or partially obstructing) can be inferred from the position of the actuator.
One technique to determine the position of the actuator includes the use of an electromagnetic source. This electromagnetic source can be coupled to a side of the actuator. As the actuator moves longitudinally to control a valve, the electromagnetic source radiates an electromagnetic field. A set of sensors can be placed in an opposing position with respect to the electromagnetic source. A subset of the sensors may sense the electromagnetic field. Because the position of the set of sensors is predetermined, the position of the actuator can be calculated from the position of the subset of the sensors that senses the electromagnetic field.
The process of manufacturing the set of sensors is not always ideal. As a result, these sensors may be misaligned. Such a misalignment creates undesired effects in the sensing of the electromagnetic field. Undesired effects impact the calculation of the position of the actuator so that the calculated position may be imprecise. Imprecision in the calculated position of the actuator renders imprecision in the inferred status of the valve. In certain circumstances, such as the cooling of a nuclear generator or in food processing, such imprecision may lead to catastrophic results.
Thus, what is needed are systems and methods to enhance detection of the positions of actuators.
Systems and methods for detecting the position of an actuator are discussed. An illustrative aspect includes a system to detect a position of an actuator. The system includes a magnetic source coupled to the actuator radiating a field, at least two sensors to generate a response based on angles of the field, and an analyzer receptive to the response to produce an enhanced position of the magnetic source in the presence of undesired effects arising from misalignment of the at least two sensors.
Another illustrative aspect includes a method for detecting a position of an actuator. The method includes interpolating a response of at least two sensors to form a quantity that is indicative of a position of a magnetic source coupled to the actuator. The method further includes adjusting the quantity by selecting one of two compensation techniques. Each compensation technique includes forming at least one adjustment. The act of forming the at least one adjustment includes forming an amplitude component. The act of selecting includes selecting a compensation technique based on correlating a plurality of maximum slopes of the response to a plurality of amplitude components between the magnetic source and the at least two sensors. The act of selecting includes selecting a compensation technique based on correlating a plurality of minimum separations of the response to a plurality of amplitude components between the magnetic source and the at least two sensors. A minimum separation is defined to be a minimum of a plurality of separations. Each separation is defined to be a certain distance between a maximum and a minimum of a cubic fit to the response.